Experimental investigations on NOx emissions of a single-cup,Lean Premixed Prevaporized(LPP),module combustor were carried out at elevated inlet temperature and pressure up to810 K and 2.0 MPa,close to the real operat...Experimental investigations on NOx emissions of a single-cup,Lean Premixed Prevaporized(LPP),module combustor were carried out at elevated inlet temperature and pressure up to810 K and 2.0 MPa,close to the real operating conditions of aero-engine combustors.This LPP combustor adopts centrally staged fuel injections which could produce separated stratified swirling spray flame.In the NOx emissions measurements,the ranges of dome equivalence ratio and fuel stage ratio were from 0.55 to 0.58 and 8%to 24%,respectively.The optical diagnosis on separated stratified swirling spray flame were carried out with fuel stage ratio changing from 15%to 30%.Therefore,NO*and OH*chemiluminescence images were obtained.The results show that NOx emissions increase with the increase of the fuel stage ratio.And from the chemiluminescence images,the main flame and pilot flame are found weakly coupled.The pilot flame plays a significant role in NOx emission production because of its higher adiabatic flame temperature.Based on the results of chemiluminescence optical tests,a new NOx emission prediction model is proposed based on the Lefebvre’s single flame model The estimate of local equivalence ratio of the pilot stage’s nonpremixed flame is modified considering the characteristics of spray combustion,and a"PLUS"emission prediction model suitable for separated stratified swirling spray flame is obtained.Compared to the experimental data,the"PLUS"model exhibits a good prediction in a range of±13%of deviation.展开更多
The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated. Combustion instabilities result from the coupling between acoustic waves and unsteady combustion heat rele...The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated. Combustion instabilities result from the coupling between acoustic waves and unsteady combustion heat release. Sometimes the phenomenon happens in afterburners of aeroengine and rocket engine, and it always causes damage to flame holders, liner seetions and other engine components. Passive methods, such as perforated liner, are often used to suppress such instabilities in application. In this article, first, a burner testbed is built in order to study the characteristic of this phenomenon. The unstable frequencies and unsta- ble area are investigated experimentally. Then an analytical model, based on "transfer element method", is developed and the numerical results are compared with those from experiments. At last the perforated liner is applied to the burner to suppress the instabilities. The results show that the sound pressure can be greatly reduced by the perforated liner.展开更多
基金supported by the National Natural Science Foundation of China(No.91641109).
文摘Experimental investigations on NOx emissions of a single-cup,Lean Premixed Prevaporized(LPP),module combustor were carried out at elevated inlet temperature and pressure up to810 K and 2.0 MPa,close to the real operating conditions of aero-engine combustors.This LPP combustor adopts centrally staged fuel injections which could produce separated stratified swirling spray flame.In the NOx emissions measurements,the ranges of dome equivalence ratio and fuel stage ratio were from 0.55 to 0.58 and 8%to 24%,respectively.The optical diagnosis on separated stratified swirling spray flame were carried out with fuel stage ratio changing from 15%to 30%.Therefore,NO*and OH*chemiluminescence images were obtained.The results show that NOx emissions increase with the increase of the fuel stage ratio.And from the chemiluminescence images,the main flame and pilot flame are found weakly coupled.The pilot flame plays a significant role in NOx emission production because of its higher adiabatic flame temperature.Based on the results of chemiluminescence optical tests,a new NOx emission prediction model is proposed based on the Lefebvre’s single flame model The estimate of local equivalence ratio of the pilot stage’s nonpremixed flame is modified considering the characteristics of spray combustion,and a"PLUS"emission prediction model suitable for separated stratified swirling spray flame is obtained.Compared to the experimental data,the"PLUS"model exhibits a good prediction in a range of±13%of deviation.
基金National Natural Science Foundation of China (50890181)Aeronautical Science Foundation of China (2009ZB51)
文摘The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated. Combustion instabilities result from the coupling between acoustic waves and unsteady combustion heat release. Sometimes the phenomenon happens in afterburners of aeroengine and rocket engine, and it always causes damage to flame holders, liner seetions and other engine components. Passive methods, such as perforated liner, are often used to suppress such instabilities in application. In this article, first, a burner testbed is built in order to study the characteristic of this phenomenon. The unstable frequencies and unsta- ble area are investigated experimentally. Then an analytical model, based on "transfer element method", is developed and the numerical results are compared with those from experiments. At last the perforated liner is applied to the burner to suppress the instabilities. The results show that the sound pressure can be greatly reduced by the perforated liner.
